High speed telepicture system



June 1, 1937. I w. e. H. FINCH 2,082,692

HIGH SPEED TELEPICTURE SYSTEM Filed March 9, 19156 2 Sheets-Sheet 1 i 6663 21 62--@ l0 OAMPLIFIERY: v l'l'l'l'l'l'fil'l'l'F- Q 7 5 4 54 56 IAMPLiFlER 14 15 15 20 AND M 15 4 I MODULATOR MODULATOI% IZRANSMITTE W 1032 42 2 26 4s 33 T V v 68 LINEAR A.F. R42 27 355; I OSCILLATOR05CILLATOR V'VOLTS INVENTOR W/zU/JM 6. H. F/NCH ATTORNEY June 1, 1937.w. ca. H. FINCH 2,082,692

HIGH SPEED TELEPICTURE SYSTEM Filed March 9, 1936 2 Sheets-Sheet 2MARGINAL RECEIVER l y QSFOAMPLIFIER f 6" OOSCILLATOE Q2227)! ,103

110 INVENTO I/V/ZZMJM 61H F/IVOL/ BY g 2 1 I ATTORNEY 1'. e. Ml)

li'ntcnted dune Iii This invention. relates to teiepic'ture sys' moreparticularly, relates b9 high speed ture communication by elec ronicscannin Ecctrical telepicture signals, prior syste s employed mechanicalscanning operations whereby a narrow beam of light was traced over thepioture elements and. corresponding variations in the light beamintensity were converted to telepicture signals by photoelectric means.In some systems the picture record was mounted upon a drum; in othersystems the picture sheet was successively advanced past an oscillatingscanning means which moved transversely with respect to he sheet wherebysuccessive transverse scanning operations were perfected. Correspondingscanning operations were produced at the receiving station insynchronism with the transmitter scan ner for composing a telepicturereproduction. I

The speed of operation of prior telepicture systems was limited by themechanical scanning op erations and the requirements for maintaining thetransmitter and receiver scanning mechahism in perfect phasesynchronization. The ineria of the moving mechanical components and themechanical synchronizingoperations have limited these systems to speedsof the order of 100 to 150 lines per minute for quality reproduction. Icontemplate eliminating substantially all of the mechanical scanning andsynchronizing elements in a telepicture system, which permits muchhigher transmission speeds.

In carrying out my present invention, a cathode ray tube is used togenerate a scanning beam which is focused upon a picture film. The beamis caused to oscillate across the film so as to successively traversethe picture elements whereby a photoelectric cell may be actuated. Thefilm is automatically advanced by an amount equal to the width of ascanning line at the end of each scanning operation. A synchronizingimpulse is simultaneously generated for advancing a correspondingreceiving film at a remote station. Each successive line of thereceiving film is exposed to a cathode ray image of the telepicturesignals from the transmitting station in a manner to be described indetail hereinafter. A telepicture reproduction is had with either a halftone or con-- tinuous tone shading as will be set forth.

Accordingly. an object of my invention is to provide a novel telepicturesystem.

Another object of my invention is to provide a novel telepicture systemutilizing electronic scanning and synchronization operations.

Still another object of my invention is to pro vide a novel electronichigh speed. telepicture sys- A further object of my invention is toprovide a novel continuous high speed telepicture system.

These and other objects of my invention will become apparent in thefollowing description in connection with the drawings in which:

Figure 1 is a schematic illustration of a preferred embodiment of anelectronically scanned telepicture system in accordance with my presentinvention.

Figure 2' is a characteristic curve of the linear sweep oscillatorvoltage output.

FigureB is a schematic representation of the scanning operation of thepicture film during transmission.

Figure is a perspective illustration of a preferred photoelectric tubefor translating the scanhing beam picture impulses to correspondingtelepicture signals.

Figure 5 is a graphical illustration of a typical telepicture signal fora single line of scanning.

Figure 6 is a schematic diagram of an electronically scanned receivingtelepicture system for translating the telepicture signals of thetransmitter in Figure 1.

Figure 7 is a representation of the scanning operation during thereception of the telepicture signals.

Figure 8 is a diagrammatic representation of a preferred light filter orscreen at the telepicture receiver.

Referring to Figure 1, the cathode ray tube It) generates an electronbeam II which is caused to traverse a fluorescent screen l2 at one endof the tube id. The generation of the electron beam ill is familiar tothose skilled in the electronic art and is diagrammatically illustrated.The cathods i3 is heated by the heater M which is connected to asuitable battery supply, not shown. The first anode i5 concentrates theemitted electrons into an electron beam. The high voltage anode itaccelerates the electrons of the beam it which. passes between theelectrostatic defleeting plates Ei-ifi and ISL-2U, to the fluorescentscreen l2. A high voltage direct current potential source 2! suppliesthe operating potentials for the electrodes of the cathode ray tube ID.A potentiometer 22 is connected across the battery 2i. The high voltageanode I6 is connected to the positive end of the potentiometer 22, whichend is also connected to ground potential in my preferred embodiment.The first anode I5 is connected to a suitable intermediate positivepotential by variable contact 23. The control grid l deflecting platessweep characteristic curve 5 across screen I2.

-right to left of the beam Na.

25 is suitable negatively biased by tap 24 on the potentiometer 22.Deflecting plates I! and I9 are directly connected to ground potentialand accordingly assume the same potential as anode I6. Deflecting plateI3 is directly connected to ground. The deflecting plate 20 is connectedto ground through a high resistance 26. All the deflecting plates I! to20 accordingly have a common static potential which is at groundpotential, an operating expedient commonly employed.

The output of a linear sweep oscillator 21 is connected to deflectingplate 20 by a connection lead 23. The deflecting plates I9 and 20deflect the electron beam II horizontally; the vertical III8 are both atground potential and are ineffective in deflecting the beam. The linearsweep oscillator 21 causes the electron beam II to periodically sweephorizontally across the fluorescent screen I2. Figure 2 is the linearillustrating how the voltage applied between deflecting plates I3 and 20varies with time. The linearly rising portion III of the curvecorresponds to the constant rate at which the beam II is transverselymoved The return portion 3I of the curve corresponds to the rapid returnof the beam to the opposite end of the screen I I after the completionof its periodic traverse. The time interval represented by interceptsa--b of Figure 2 corresponds to the time in which beam II is uniformlyswept horizontally across the fluorescent screen I2. The shorter timeintercept bc represents the rapid return interval of the beam for itsperiodic excursion.

The electron beam II produces a spot of light upon the fluorescentscreen I2. The light beam 32 generated at the fluorescent screen I2 isusd as a scanning light beam for the picture film 33 to be transmitted.The light beam 32 is focused by a lens. system 34 upon a narrow portionor line segment of the film 33. The fllm 33 alters the intensity of thelight beam 32 passing thru it according to the shading of the pictureelements being transmitted. A photoelectric cell 35 intercepts the beam32 and generates electrical signals varying in accordance with theelemental shading of the film 33.

Figure 3 is a schematic illustration of the manner in which theelectronic scanning is performed in accordance with my presentinvention. The film 33 is somewhat narrower than the diameter of theface I2 of the cathode ray tube I0. Dashed line Ila represents theexcursion, transverse to the film 33, of the electron beam II across thefluorescent screen I2. It will be understood that the trace of theelectron beam Ila upon the fluorescent screen I2 will be visuallyevidenced as a brilliant line of light. The excursion a--b' of the pathIIa from right to left, corresponds to the time interval a-b of Figure2. The return sweep represented by the time interval b-c corresponds tothe return sweep b--a, from The portion ac' of the beam Ila correspondsto the electronic scanning period for the picture film 33. The

portion c-b' of beam Ila corresponds to the synchronizing period to behereinafter described in detail.

The fluorescent screen I2 is designed to have a low persistence so thatthe excursion of the electron beam across the path I I a will notproduce a continuous line of light but rather a moving point so that thebeam of light 32 projecting through the film 33 will correspond to theelemental shading of the picture intercepted by the path of the beam.The moving should be brilliant diameter.

33. tures are to be scanned If the transmitted picwith a detailcorrespond ingto lines per inch, then the diameter of the focusedscanning point upon film 33 will correspondingly be one-hundredth of aninch. It is important that the persistence of the fluorescent screen I2be low so that an effective moving scanning point or beam 32 isprojected through film 33 to insure the generation of telepicturesignals in accordance with the elemental shading of the picture.

The photoelectric tube 35 which I prefer to employ is illustrated inFigure 4. Tube 35 comprises two photo-sensitive cathodes 36 and 31. Thecathode 36 responds to the light beam projecting through the film 33corresponding to the portion a'-c of Figure 3 and represented thereon bythe dotted section 36. The photosensitive cathode 31 is shorter inlength and is represented by the dotted section 3'! in Figure 3 andcorresponds in length to the portion c'-d of the light beam Ila.Photoelectric tube 35 has a common anode 3B.

The telepicture signals generated between the electrodes 36-38 of tube35 are conducted to an amplifier and modulator stage 40 by loads 4 I--42(Figure 1). An audio frequency oscillator 43 is impressed uponamplifier-modulator stage 40 by leads -45. The frequency of oscillator43 may for example be 3000 cycles. The type of modulator at stage 40which I prefer to employ is commonly termed screen grid modulation. Aswill be understood by those skilled in the art, signals at the output46-4I of stage 40 will be at a minimum intensity when a dark picturesegment is being transmitted and a large signal intensity willcorrespond to a light picture segment. Figure 5 is a graphicalrepresentation of a typical signal which may be produced at the output46-4'I of stage 40. The time interval a"-c of Figure 5 represents onescanned line of the picture on film 33. The ordinate E is the relativevoltage intensity of the telepicture signal.

The alternating current curve 50 represents the audio frequency carrierof the signal, namely 3000 cycles. Figure 5 is a schematic illustrationand is accordingly not drawn to scale. The envelope SI of the carrier 50represents the telepicture modulations superimposed upon the audiocarrier 50. The envelope to the horizontal axis as will be evident tothose skilled in the art. I sented by 52-52 corresponds to a whitepicture element; the zero intensity 53 corresponds to a black pictureelement. Intermediate picture shadings produce intermediate amplitudes.

The output 46-41 of stage 40 may be transmitted to a remote receivingstage along wire lines or by radio transmission. In Figure 1, Iillustrate a radio transmission system for the telepicture signals. Thesignals are impressed upon a radio frequency modulator stage 54 by leads46-4l. A radio frequency oscillator 55 produces a carrier wave which ismodulated by the audio frequency telepicturc signals in stage 54. Theradio frequency transmitter 56 amplifies the signals from modulatorstage 54 for transmission by antenna 51.

It is to be understood that the continuous record film 33 is stationaryduring the scanning 5i is symmetrical with respect The maximum intensityrepre (ill aoaaooa Y 3 operation and is periodically advanced past thescanning beam 32 in a predetermined manner. The film 33 is contained ina roll 90 and is automatically advanced by the stepping mechanism 6|upon the take-up roll 92. For a scanning operation of 100 lines perinch, the stepping mechanism Bl moves film 33 past beam 32 one-onehundredth of an inch at the completion" of each scanning operation. Whenthe scanning beam moves to the segment cd' (Figure 3) the beam 32 willimpinge upon the photo-sensitive cathode" 31 and produce a signal in theformof an impulse upon amplifier 93 through leads 64-65. The output66-61 of amplifier 93 is connected to the automatic advancing mechanismschematically represented at 9|. Mechanism 9i may for example be wellknown electro-magnetic periodic advancing means which is actuated by theelectrical impulses produced at the end of each scanning excursion Ilaof the electron beam II as will be understood. The film 33 isaccordingly advanced the proper amount during this interval so that theadjacent line may be scanned during the next cycle of operation.

The signal impulse produced at electrodes 31- 39 is also used for thesynchronizing impulse at the remote receiving station for automaticallyadvancing the receiving record sheet in a manher to be described. Thisimpulse is accordingly impressed upon the amplifier-modulator stage 49by means of a unidirectional impedance'dev'ice 10 connected betweenleads 65 and 4| and conductive in the direction towards the amplifierstage 49. The unidirectional impedance 19 may be a buffer stage ofthermionic amplification or a rectifier. A unidirectional impedance isused to prevent the picture signals generated at electrodes 36-39 frombeing impressed upon the amplifier 63. The magnitude of the impulseimpressed upon amplifier 49 is greater than that of any correspondingtelepicture signals so that the receiving station may selectivelyrespond to this signal for operating the automatic film advancingmechanism.

Figure 6 is a schematic representation of the electronic telepicturereceiving system to be used for translating the telepicture signalsradiated from the transmitter of Figure l by the antenna 56. The radioreceiver 1| amplifies the radio frequency signals impressed upon itsantenna 12 and rectifies the modulated radio frequency carrier signals.The output 13-14 of receiver 1| corresponds in signal wave form to thatatthe output 46-41 of amplifier-modulator stage 49 of the transmitter.The output 13-14 is the audio carrier modulated in accordance with thepicture shading being transmitted, corresponding for example, to itsgraphical representation in Figure 5. Connection lead impresses thetelepicture signals upon vertical deflecting plate 19. The oppositevertical deflecting plate 11 is connected to ground through lead 19. Ahigh resistance 19 connects deflecting plate 19 to electrostatic groundpotential. The plates 16-11 are accordingly at a common static potentialwith respect to the high potential anode 99, namely at ground potential.The receiver cathode ray tube BI is similar to the correspondingtransmitter tube Ill. The electrode potential supply is from thepotentiometer 92 connected across the high voltage supply 83, thepositive terminal of which is connected to ground. The first anode 94and the control grid 85 are connected to suitable potential points onthe potentiometer 82. The electron beam 86 is generated at the cathode81 and focused upon the fluorescent screen in the well known manner. Thehorizontal deflecting plates 99-99 are actuated by the linear sweeposcillator 9|. The output of sweep oscillator 9| is connected to thehorizontal deflecting plate 39 by lead The frequency of linear sweeposcillator 9| is adjusted close to that of the frequency of thetransmitter sweep oscillator 21. Oscillator 9l is impulse excited by thesynchronizing signals so that is will have the exact frequency of thetransmitter scanning frequency. The electron beam 96 will accordingly beoscillated horizontally across the center of the fluorescent screen 99by deflecting plates 99-99. A marginal amplifier 93 is connected to theoutput 13-14 of the receiver 1! by input leads 94-95. Marginal amplifier93 is suitably biased so as to respond only to a predetermined amplitudeof input signals, namely to the amplitude of the synchronizing signals.Since the synchronizing signals are greater in amplitude than any of thetelepicture variations, amplifier 93 will respond only to thesynchronizing impulses as will beunderstood by those skilled in the art.The output 99-91 of marginal amplifier 93 will accordingly beperiodically amplified impulses corresponding to the transmittedsynchronizing impulses during scanning period c'-d' (Figure 3). Theoutput 99-91 is connected to the linear sweep oscillator 9| by leads99-99 to provide the frequency synchronization therefor in a well knownmanner. The horizontal scanning action of electron beam 98 willcorrespond to that of electron beam H at the transmitter. The phaseadjustment of beam 96 is automatically provided by proper design of theimpulse excited linear sweep oscillator 9| in relation to thepredetermined occurrence of the periodic synchronizing impulse at theend of each scanning line.

The incidence of electron beam 89 upon fiuorescent screen 99 willproduce a brilliant spot of light which is suitably focused by lenssystem I09 upon the receiving film NH. The continuous film lOl iscontained upon take-up roll I92 and is automatically stepped past thescanning beam by stepping mechanism H13. Mechanism I93 is similar to thestepping mechanism 9| of the transmitter and is electrically actuated bythe amplified synchronizing impulses from the output 96-91 of amplifier93. Film I9i is advanced in the present example one one-hundredth of aninch at the end of each scanning line operation.

Film I9! is placed opposite the fluorescent face 99 of tube 8| in aposition corresponding to that of the transmitter represented by Figure3. Points (1', c, and b of Figure 7 correspond to the similarly markedpoints of Figure 3. The interval a'-c' is equal to the width of the filmHI, for example, six inches. The transmitter film 33 would also be sixinches wide. The interval c-b' corresponding to the synchronizingimpulse period may be one inch in length.

The vertical deflecting plates 19-11, actuated by the telepicturesignals will superimpose upon the horizontally oscillated electron beam89, a motion corresponding to the wave form 50 represented in Figure 5.The fluorescent image of the actuated beam 99 will appear upon screen 89in the form represented by curve I93. The transmitter linear sweeposcillator 21 is electrically,

coupled to the audio frequency oscillator 93 by 1 iii lat'ir 4'3 il' ybe tuned to .illl'lil cycles and the ator concl, iiilti to i.

v at

A light linings "1th,... .y signal all (.wcordingly not be ire-- hiredupon film Hill and biaclt picture element will result thereon, A whitepicture element represented by the maxin'lum image width IDS-405corresponds to the signal intensity representation 52--5Z in Figure 5.Focusing system I00 is dcsigned to recluccthe light image width IBIS-I06to the width of the scanning line impressed upon film IOI, namely oneone-hundredth of an inch. Intermediate picture shadings as hereinabovedescribed, will be represented by intermediate light image widths on thefluorescent screen 88. The picture shading recorded on film IN isproportional to the width of the light image I04 opposite the particularelement of the line during scanning thereof.

If the frequency of the picture carrier is relatively high, the imageI04 thereof will be represented as a light area having an envelopec0rresponding to the picture shading modulation. A contihuous tonereproduction will accordingly resuit. On the other hand, if the picturecarrier frequency is relatively low, a distinct sinusoidal wave formsimilar to the illustration I04 will result with a similarly shapedenvelope I05. A discrete point by point or half-tone reproduction willresult due to the non-contiguous light image. This effect may beincreased by shielding the upper or lower half of the light image I04.

The persistence of fluorescent screen 88 should be low enough so thatthe light image I04 of each successive line scanned will disappear inthe interval between scanning impressions, namely, during thesynchronizing period c'-b' and the sweep return interval 3| (Figure 2).The important feature of my present invention resides in therepresentation of the picture shading by a corresponding electronicallyproduced varying width light image which is focused to a narrow scanninglight beam upon a sensitive picture film. To compensate for a non-linearpicture shading translation, a light filter or screen I01 may beinterposed between the signal Image I04 and the film IOI. Figure 8illustrates a preferred shading for the light filter or screen I01. Theouter portions I08 of screen I01 are transparent. A gradual reduction oflight trans -mission is effected between the outer portions I00 and thecentral portion I013. The effectiveness oi the varying widths of lightimage I04 on screen 08 upon. the film |0I is accordingly predeterminedby the light transmission character istic of the screen I01. In theillustrated screen I01, the portions of the light image I04 on screen 88furthest away from the horizontal axis cz-b will be more effective thanthe portions nearer to axis a'-b as will be understood. By drawing anarrow opaque line IIO across the center of screen I01, the ineffectivefluorescent section r a--b of screen 08 may be dispensed with soaosarniul or oi" present to those skilled l ctrouic V including meansfor generating an electron beam, and means for oscillating said boom inone direction at a pro-- determined rate transversely a picture film tobe transmitted with one oscillation for each line of scanning; aphotoelectric cell in operative relation with said scanner and saidpicture for generating teiepicture signals of individual lines ofscanning in accordance with the shading of said picture as said scannerscans the picture; a source of carrier current; means for modulatingsaid carrier current in accordance with said tclepicture signals; and areceiver comprising a corresponding electronic scanner including meansfor generating an electron beam, means for oscillating said receiverbeam in one direction at said predetermined rate with one oscillationcorresponding to each of said lines of scam ning, and means forsimultaneously moving said receiver beam transverse to said oscillatingdirection in accordance with the received picture modulated carriercurrent whereby the width along any section of the image is proportionalto the degree of picture signal modulation.

2. In a telepicture system, a transmitter com prising an electronicscanner including means for generating an electron beam, and means foroscillating said beam in one direction at a predetermined ratetransversely of a picture film to be transmitted with one oscillationfor each line of scanning; a photoelectric cell in operative relationwith said scanner and said picture for generating telepicture signals ofindividual lines of scanning in accordance with the shading of saidpicture as said scanner scans the picture; a source of carrier current;means for modulating said carrier current in accordance with saidtelepicture signals; and a receiver comprising a correspondingelectronic scanner including means for generating an electron beam,means for oscillating said receiver beam in one direction at saidpredetermined rate with one oscillation corresponding to each of saidlines of scanning. and means for simultaneously moving said receiverbeam at right angles to said oscillating direction in accordance withthe received pic- .ure modulated carrier current whereby the width alongany section of the image is proportional to the degree of picture signalmodulation.

3. In a telepicture system, a transmitter comprising an electronicscanner including means for generating an electron beam, and means foroscillating said beam in onev direction at a pre determined ratetransversely of a picture film to be transmitted with one oscillationfor each line of scanning; a photoelectric cell in operative relationwith said scanner and said picture for generating telepicture signals ofindividual lines of scanning in accordance with the shading of saidpicture as said scanner scans the picture; a source of carrier current;means for modulating said carrier current in accordance with saidtelepicture signals; a receiver comprising a corill light tracing alongsuccessive thin lines for re- 15 producing the transmitter picture onsaid record sheet.

4. In a telepicture system, a transmitter comprising an electronicscanner including a cathode ray tube having a fluorescent screen, means20 for generating an electron beam and means for oscillating said beamin one direction at a predetermined frequency with one oscillation for II each line of scanning across said fluorescent screen for generating amoving scanning point of 25 light transversely of a picture fllm to betransmitted, means for moving said picture at right angles to the lineof oscillation of said beam oetween successive oscillations thereof; alens system interposed between said fluorescent screen and said picturefllm for focusing said moving point of light on said picture film; aphotoelectric cell in operative relation with said scanner and saidpicture for generating telepicture signals of individual lines ofscanning in accord- 35 ance with the shading of said picture as saidscanner scans the picture; means for generating an audio frequencycarrier current which is a multiple of said oscillating frequency, meansfor producing a synchronizing impulse between successive lines ofscanning, means for modulating said carrier current by said telepicturesignals; a receiver comprising a corresponding electronic scannerincluding a cathode ray tube having a fluorescent screen, means forgenerating an electron beam, means responsive to said synchronizingimpulses for oscillating said receiver beam in one direction at saidpredetermined rate with one oscillation corresponding to each of saidlines of scanning for generating a moving point of light on the screentransversely of a light sensitive record sheet, and means forsimultaneously moving said receiver beam at right angles to saidoscillating direction in accordance with the picture modulations of thereceived signals for pro- 55 ducing an' individual stationary lighttracing corresponding to successive lines of scanning of the picture,the tracing of each successive line being generated in substantiallythesame area of said receiver screen.

5. In-a telepicture system, a transmitter comprising an electronicscanner including a cathode ray tube having a fluorescent screen, meansfor generating an electron beam and means for oscillating said beam inone direction at a predetermined frequency with one oscillation for eachline of scanning across said fluorescent-screen for generating a movingscanning point of light transversely of a picture film to betransmitted, means for moving'said picture at right angles to the lineof oscillation of said beam between successive oscillations thereof; alens system interposed between said fluorescent screen and said picturefilm for focusing said moving point of light on said picture fllm; aphotoelectric cell 75 in operative relation with said scanner and saidpicture for generating telepicture signals of individual lines ofscanning in accordance with the shading of said picture as said scannerscans the picture; means for generating an audio frequency carriercurrent which is a multiple of said oscil- -lating frequency, means forproducing a synchronizing impulse between successive lines of scanning,means for modulating said carrier current by said telepicture signals; areceiver comprising a corresponding electronic scanner including acathode ray tube having a fluorescent screen, means for generating anelectron beam, means responsive to said synchronizing impulses foroscillating said receiver beam along a single plane at saidpredetermined rate with one oscillation corresponding to each of saidlines of scanning for generatingf'a moving point of light on the screentransversely of a' light sensitive record sheet, means forsimultaneously moving said receiver beam at right angles to said planein accordance with the picture modulations of the received signals forproducing an individual stationary light tracing corresponding tosuccessive lines of .scanning of the picture; and means for affectingsaid light sensitive sheet by said light tracing along successive thinlines for reproducing the transmitter picture on said record sheetcomprising a lens system interposed between said fluorescent screen andsaid sheet.

6. In a telepicture system, a transmitter comprising an electronicscanner including a cathode ray tube having a fluorescent screen, meansfor generating an electron beam and means for oscillating said beam inone direction at a predetermined frequency with one oscillation for eachline of scanning across said fluorescent screen for generating a movingscanning point of lighttransversely of a picture fllm to be transmitted,means for moving said picture at right angles to the line of oscillationof said beam between successive oscillations thereof; a lens systeminterposed between said fluorescent screen and said picture fllm forfocusing said moving point of light on said picture film; aphotoelectric cell in operative relation with said scanner and saidpicture for generating telepicture signals of individual lines ofscanning in accordance with the shading of said picture as 'said scannerscans the picture; means for generating an audio frequency carriercurrent which is a multiple of said oscillating frequency, means forproducing a synchronizing impulse between successive lines ofscanning-means for modulating said carrier current by said telepicturesignals; a receiver comprising a corresponding electronic scannerincluding a cathode ray tube having a fluorescent screen, means forgenerating an electron beam, means responsive to said synchronizingimpulses for oscillating said receiver beam along a single plane at saidpredetermined rate with one oscillation corresponding to each of saidlines of scanning for generating a moving point of light on the screentransversely of a light sensitive record sheet, means for simultaneouslymoving said receiver beam at right angles to said plane in accordancewith the picture modulations of the received signals for producing anindividual stationary light tracing corresponding to successive lines ofscanning of the picture and means for affecting said light sensitivesheet by said light tracing along successive thin lines for reproducingthe transmitter picture on said record sheet comprising a lens systeminterposed between said fluorescent screen and said sheet for focusingsaid light tracing plane at said predetermined rate upon said sheetalong a thin line, and means responsive to said synchronizing impulsefor advancing said record sheet between successive lines of scanning.

7. In a telepicture system, a transmitter comprising an electronicscanner including a cathode ray tube having a fluorescent screen, meansfor generating an electron beam and means for oscillating said beam inone direction at a predetermined frequency with one oscillation for eachline of scanning; across said fluorescent screen for generating a movingscanning point of light transversely of a picture fllm to betransmitted, means for moving said picture at right angles to the lineof oscillation of said beam between successive oscillations thereof; alens system interposed between said fluorescent screen and said picturefllm for focusing said moving point of current by said telepicturesignals; a receiver comprising a corresponding electronic scannerincluding a cathode ray tube having a fluorescent screen, means forgenerating an electron beam, means responsive to said synchronizingimpulses for oscillating said receiver beam along a single with oneoscillation corresponding to each of said lines of scanning forgenerating a moving point of light on the screen transversely of a lightsensitive record sheet, means for simultaneously moving said picturemodulations of the received signals for producing a stationary lightwith received picture modulated carrier current whereby the width alongany section 'Of the im age is proportional to the degree of picturesignal modulation.

9. In a telepicture system, a receiver comprising an electronic scannerincluding a cathode ray tube having a fluorescent screen, means forgenerating an electron beam, means for oscillating said beam in onedirection at a prcdeter mined rate, with one oscillation correspondingto an individual line of scanning for generating a moving point of lighton the screen transversely of a light sensitive record sheet, and meansfor simultaneously moving said receiver beam at right angles to saidoscillating direction in accordance with received picture modulatedcarrier current whereby the width along any section of the image isproportional to the degree of picture signal modulation; and means foraffecting 10. In a telepicture system, a receiver comprising anelectronic scanner including a cathode tube having a fluorescent screen,means for posed between said fluorescent screen and said sheet.

11. In a telepicture system, a receiver comprising an electronic scannerincluding a cathode ray tube having a fluorescent screen, means forsheet, means for simultaneously moving said receiver beam at rightangles to said oscillating direction in accordance with received picturemodulated carrier current whereby the width along any section of theimage is proportional to the degree of' picture signal modulation; andmeans for affecting said light sensitive sheet by said light tracingalong successive thin lines for reproducing the transmitter picture onsaid record sheet comprising a lens system interposed between saidfluorescent screen and said sheet for focusing said light tracing uponsaid sheet along a thin line, means for advancing said record sheetbetween successsive lines of scanning, and a light filter interposedbetween said tracing and said record sheet for predetermining the actionof said light tracing on said record sheet.

WILLIAM G. H. FINCH.

